fix a small get_history bug

client/chat.js

@@ -78,6 +78,7 @@ window.onload = () => {
     if (!window.earliestMessage) window.earliestMessage = msg.id;
   });
   window.socket.on("get_history", (msg) => {
+    if (msg.messages.length > 0) {
       window.earliestMessage = msg.messages[msg.messages.length - 1].id;
       for (let message of msg.messages) {
         const el = document.createElement("div");
@@ -85,6 +86,7 @@ window.onload = () => {
         el.innerHTML = `<strong>${message.name}: </strong>${message.message}`;
         document.getElementById("messages").prepend(el);
       }
+    }
     if (!msg.more) document.getElementById("loadmore").classList.add("hidden");
   });
   window.socket.on("authenticate", swap);